I built a pair of speakers into some goggles because I thought it was so crazy that no one would've tried it yet. They've gotten a great response from friends, so I now share my wisdom with you. Yes, they do fit in front of your eyes, but they're exactly as difficult to see out of as you'd expect. Also, they're a little heavy to wear in front of your face all day. But if you build them, they WILL make you cool. Now be prepared to be the envy of the next block party!

Skills:

This project requires some pretty fine soldering skills. On the plus side, there aren’t too many wires, and there’s nothing to program. While we’re at it, there’s no welding, cooking, or heavy lifting either, so if those things intimidate you, no worries.

Parts:

To finish this project, you’ll need a pair of goggles. I used German safety goggles. They were great for this project because the frames are circular - no nose indent to get in the way. To finish it completely, you’ll also need:

Bluetooth receiver module like this one - BLK-MD-SPK-B This can do more than receive music, but it does that well. $6.28
Amp - the one I used is sold out, but this one is cheaper and looks easier to use. It’ll save you from having to desolder terminal blocks, which is no fun. $2.11
Drivers - These match the silver goggles. Plus they fit. $3.79
Hook up wire - Old CAT5 cable works great if it’s stranded. Any wire will do, but I recommend stranded 22-24 awg. Various colors are a plus.
Magnet wire - A new roll might set you back $8, but lasts forever if you’re not wrapping coils with it.
JST connector/Battery jack - I got red ones because sure why not. The angle of jack isn't too important here. $4.99
Lithium Ion Polymer (LiPo) Battery - I turn to trustworthy sources when it comes to batteries. The 150mA one powers the goggles for about an hour. $5.95
Button or switch - nothing fancy. One like this simple toggle switch will do. $1.55
47uf Capacitor
Hook and loop - it’s Velcro. Squares are handy.

Cost

Total cost including goggles is around $40, depending on what you have in your useful parts bin/glove compartment/wastebasket.

Step 1: Here's the Plan

Non-branded modules from no-name suppliers tend to leave out formalities like instruction sheets. The second image has actual labels for the board and what we’ll be building. This board can do more than we're using it for here. For more info on what that is and how to do it, check out ElecFreaks, which I found super helpful.

Step 2: Leads Get Connected to the Bluetooth Module

Wires move electrical potential from one end to the other via capillary action [possibly false]. In the case of signal wires on the bluetooth, we don’t need too many electrons, but we do need small enough wire that it won’t bridge traces. This is one of those times magnet wire comes in handy.

Remove Enamel and Tin Wires

A tricky thing about magnet wire is that the insulation is a thin coating of enamel, and wire strippers won’t work. I’ve heard of people sanding it off, but my favorite method is to glop up solder on the tip of your iron and hold the wire inside the blob. This’ll burn off the enamel and leave a well-tinned tip. If you’ve ever soldered to headphone wire, you know the drill.

Solder Carefully

Using the smallest soldering tip you have, make the pads and wires become one.

Finally, add a 47uf capacitor to the power connections to filter out the impure electrons.

Step 3: The BT Chip Connects to the Amp Chip

Getting music in signal form off the receiver is nice, but there’s not enough energy juice in there to drive the speakers. You’re gonna need to cram an amp in there too. True, you could make your own out of an LM386 or similar (a useful thing to learn), but one of the most important things about the internet is that it enables anyone to buy a cheap class-D amplifier from the comfort of their own autocar, for less than you could pay for a piece of toast.

So grab and hook up your amplifier. You’ll find that the amp module is not only easier to solder to, but easier to hold on to as well.

Test as you go. Remember kids, at any stage you can test the project in, test the project. Catching mistakes early should make you feel smart. And finding successes early will make you feel even better than that.

Step 4: For More Power

Now install the battery socket (to the circuit, not the battery). And wire in the switch. Strictly speaking, it doesn’t matter which way you put in the switch, but you should probably do it so you’ll remember which side is “on” (I confess, I still check mine sometimes).

Another sweet thing about these metal goggles is the louvers on the side are great for mounting switches. If yours don’t have those, I guess you can drill a hole.

Step 5: Speakertime

Sticking wires on to the speakers follows pretty much the same pattern. But we saved it for last because the speaker wires actually get threaded through the goggle eyeholes. This is what the hookup wire is for; much easier to deal with than magnet wire. I suggest attaching wires on the speaker side first, but do what you feel you need to do.

Step 6: Final Touches

Because I try to avoid strapping bombs to my face, I always attach the LiPo battery outside the goggles. A little square of Velcro brand hook and loop makes for a slim and fast (lazy) quick-change mount.

Use the hacker's thermal prototyping compound of choice (hot glue) and stick the things in place so they won't come up again.

Now plug battery lead into the part from before and flip the switch.